1. APES Lesson 7 - Demogrphy
AP Environmental Science
Mr. Grant
Lesson 45
Outdoor Air Quality

2. Mastery Check
Where is the “ozone layer” located? How and why is stratospheric ozone beneficial for people, whereas tropospheric ozone is harmful?

3. Objectives: Define the term Volatile Organic Compounds (VOCs).
Identify major pollutants, outline the scope of outdoor air pollution, and assess potential solutions.

4. Define the term Volatile Organic Compounds (VOCs).
Carbon-containing chemicals used in and emitted by vehicle engines and a wide variety of solvents, industrial processes, household chemicals, and consumer items.
Examples include: Acetone (nail polish remover), Benzene (cigarettes, gasoline), Ethylene glycol (antifreeze, detergents), Formaldehyde (shampoos, sunblock, cosmetics, baby wipes), Methylene chloride (wood floor cleaners, spray shoe polish), Perchloroethylene (spot removers), Toluene (paints, paint thinners, nail polish), Xylene (synthetic fiber production, papermaking), 1,3-butadiene (internal combustion engines exhaust, tobacco smoke)

5. Identify major pollutants, outline the scope of outdoor air pollution and assess potential solutions.
Natural sources such as fires, volcanoes, and windblown dust, pollute the atmosphere. Human activity can worsen some of these phenomena.
The pollutants we admit include primary and secondary pollutants from point and non-point sources.
To safeguard public health under the Clean Air Act, the U.S. EPA and state governments monitor emissions of six major pollutants: carbon monoxide, sulfur dioxide, nitrogen oxides, volatile organic compounds, particulate matter and lead.
Agencies also monitor ambient concentrations of the six criteria pollutants: carbon monoxide, sulfur dioxide, nitrogen dioxide, tropospheric ozone, particulate matter and lead.

6. Identify major pollutants, outline the scope of outdoor air pollution and assess potential solutions.
Thanks to public policy and to pollution control technologies, emissions in the United States have decreased substantially since 1970, and ambient air quality is much improved in most respects.
Emissions of 187 toxic air pollutants are also declining, but they still pose health risks.
The U.S. EPA is taking early steps toward regulating greenhouse gases as pollutants because they drive climate change.
Industrializing nations such as China and India are experiencing some of the world’s worst air pollution today.

7. Identify major pollutants, outline the scope of outdoor air pollution and assess potential solutions.
Industrial smog produced by fossil fuel combustion is still a problem in urban and industrial areas of many developing nations.
Photochemical smog is created by chemical reactions of pollutants in the presence of sunlight. It impairs visibility and human health in urban areas.
Cities such as Los Angeles and Mexico City are taking bold steps to address photochemical smog.

8. Outdoor Air Quality
Air pollutants = gases and particulate material added to the atmosphere
Can affect climate or harm people or other organisms
Air pollution = the release of air pollutants
Outdoor (ambient) air pollution = pollution outside
Has recently decreased due to government policy and improved technologies in developed countries
Developing countries and urban areas still have significant problems
Greatest air pollution problem may be our emission of greenhouse gasses

9. Natural sources can pollute
Fires pollute the atmosphere with soot and gases
Over 60 million ha (150 million acres) of forests and grasslands burn per year
Human influence makes fires more severe
Fuel buildup from fire suppression
Development in fire-prone areas (such as chaparral)
“Slash-and-burn” agriculture causes fire where they might not naturally occur

10. Natural sources can pollute
A severe El Niño in 1997 caused unprecedented forest fires that sickened 20 million and caused a plane to crash
Climate change will increase drought and fires
Volcanoes release particulate matter, sulfur dioxide, and other gases that can remain in the air for months or years
Aerosols = fine droplets of sulfur dioxide, water, oxygen
Reflect sunlight back to space
Cool the atmosphere and surface

11. Natural sources can pollute
Dust storms occur when wind sweeping over arid land sends huge amounts of dust aloft
Unsustainable farming and grazing contribute by promoting erosion and desertification
Trade winds blow dust from Africa across oceans, providing nutrients to the Amazon and infecting coral reefs in the Caribbean with fungal spores

13. We create outdoor air pollution
Point sources = specific spots where large quantities of pollutants are discharged (power plants and factories)
Non-point sources = more diffuse sources, consisting of many small sources (automobiles)
Primary pollutants = pollutants that are directly harmful and can react to form harmful substances (soot and carbon monoxide)
Secondary pollutants = pollutants that form when primary pollutants interact or react with components of the atmosphere
Tropospheric ozone and sulfuric acid

14. We create outdoor air pollution
Residence time = the time a pollutant stays in the atmosphere
Pollutants with brief residence times exert localized impacts over short time periods
Particulate matter, automobile exhaust
Pollutants with long residence times exert regional or global impacts
Pollutants causing climate change or ozone depletion

16. Clean Air Act legislation addresses pollution in the United States
Clean Air Act of 1963 funded research and encouraged emissions standards
The Clean Air Act of 1970
Set standards for air quality and limits on emissions
Provided funds for pollution-control research
Allowed citizens to sue parties violating the standards
The Clean Air Act of 1990 strengthened regulations for auto emissions, toxic air pollutants, acidic deposition, stratospheric ozone depletion
Introduced emissions trading for sulfur dioxide

17. Clean Air Act legislation addresses pollution in the United States
The Environmental Protection Agency (EPA) sets nationwide standards for emissions and concentrations of toxic pollutants
States monitor air quality
They develop, implement, and enforce regulations
They submit plans to the EPA for approval
The EPA takes over enforcement if plans are inadequate
The EPA can prevent regions from receiving money for transportation projects if they fail to clean up their air

18. Agencies monitor emissions
State and local agencies monitor and report on six major pollutants: carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxides (NOX), volatile organic compounds (VOCs), particulate matter, and lead (Pb)
Carbon monoxide (CO) = colorless, odorless gas
Produced primarily by incomplete combustion of fuel
From vehicles and engines, industry, waste combustion, residential wood burning
Poses risk to humans and animals, even in small concentrations
Binds irreversibly to hemoglobin, preventing oxygen transport in the blood

20. Agencies monitor emissions
Sulfur dioxide (SO2) = colorless gas with a strong odor
From coal emissions from electricity generation, industry
Can form acid precipitation
Nitrogen oxides (NOx) = formed when nitrogen and oxygen react at high temperatures; includes NO and NO2
From vehicles, industrial combustion, electrical utilities
Contribute to smog and acid precipitation

21. Agencies monitor emissions
Volatile organic compounds (VOCs) = carbon- containing chemicals
Used and emitted by engines, solvents, household chemicals, and industrial processes
Can react to produce secondary pollutants

22. Agencies monitor emissions
Particulate matter = suspended solid or liquid particles
Primary pollutants: dust and soot
Secondary pollutants: sulfates and nitrates
Damages respiratory tissue when inhaled
Two size classes for particles
PM10 = less than 10 microns in diameter (dust)
PM2.5 = less than 2.5 microns (combustion products)

23. Agencies monitor emissions
Lead = heavy metal used in gasoline and industrial metal smelting
Bioaccumulates and damages the nervous system
Banned in gasoline in developed countries
Being banned in most developing countries

24. We have reduced pollutant emissions
Total emissions of the six monitored pollutants have declined substantially since the Clean Air Act of 1970
Despite increased population, energy consumption, miles traveled, and gross domestic product
Most other industrialized nations have also reduced their emissions
Reductions have been achieved by a combination of policy and technology driven by grassroots demand
Cleaner-burning engines and catalytic converters
Scrubbers = chemically convert or physically remove pollutants before they leave smokestacks

28. We have reduced pollutant emissions
Permit-trading programs and clean coal technologies reduce SO2 emissions
Phaseouts of leaded gasoline caused emissions of lead to drop 93% in the 1980s
Reduction of emission is regarded as one of the greatest accomplishments of the United States in protecting health and the environment
Shows what can be accomplished when government and industry use scientific information and listen to public demands
EPA estimates that 200,000 lives were saved between 1970 and 1990 because of cleaner air

29. Air quality has improved
EPA and states monitor outdoor air quality
Criteria pollutants = pollutants that pose especially great threats to human health
Carbon monoxide, sulfur dioxide, particulate matter, lead, nitrogen dioxide, tropospheric ozone

30. Air quality has improved
National ambient air quality standards (NAAQS) = maximum concentrations allowed in outdoor air
Nitrogen dioxide (NO2) = a highly reactive, foul- smelling reddish brown gas
Contributes to smog and acid precipitation
Along with nitric oxide (NO) is part of the chemical group called nitrogen oxides (NOX)

31. Air quality has improved
Tropospheric ozone (O3) or ground-level ozone = a colorless gas that poses health risks due to the instability of the O3 molecule
Results from interactions of sunlight, heat, nitrogen oxides, and volatile carbon-containing chemicals
Is a secondary pollutant
Is a major component of smog
Participates in reactions that harm tissues and cause respiratory problems
Is the pollutant that most frequently exceeds EPA standards

33. Air quality has improved
Air quality today is better than it has been for at least a generation
However, new pollutants are emerging as new problems, particularly greenhouse gas emissions
Many Americans live in areas where criteria pollutants still reach unhealthy levels
The air in Los Angeles county violates NAAQS for five of the six criteria pollutants

35. Air quality has improved
Much of the focus of controlling emissions is on cities, but rural residents can suffer from poor air quality
Airborne pesticides from farms
Industrial pollutants that drift from cities, factories, and power plants
Feedlots, where cattle, hogs, or chickens are raised in dense concentrations
Produce dust, methane, hydrogen sulfide, and ammonia
Create objectionable odors
People living or working nearby have high rates of respiratory illness

36. Toxic substances pose health risks
Toxic air pollutants = substances that cause cancer, reproductive defects, or neurological, developmental, immune system, or respiratory problems
The EPA regulates 187 toxic air pollutants from metal smelting, sewage treatment, industry, etc.
Includes heavy metals, VOCs, methylene chloride
Toxic air pollutants cause cancer in 1 out of 20,000 Americans
Clean Air Act regulations helped reduce emissions by more than 42% since 1990

38. Should we regulate greenhouse gasses as air pollutants?
Industrialized countries have reduced most sources of air pollution but are continuing to release vast amounts of greenhouse gasses
Warming of the lower atmosphere by greenhouse gas emission may be the largest air pollution threat we face today
Industry and utilities generate much of the emissions
All of us contribute to greenhouse gas emissions
The average U.S. vehicle driver releases close to 6 metric tons of carbon dioxide and large amounts of methane and nitrous oxide per year

39. Should we regulate greenhouse gasses as air pollutants?
In 2007, the U.S. Supreme Court ruled that the EPA could regulate greenhouse gasses under the Clean Air Act
Congress failed to pass legislation to regulate greenhouse gas emission
In 2011 the EPA introduced standards for cars and trucks and in 2012 for new coal-fired power plants

40. Should we regulate greenhouse gasses as air pollutants?
Coal and petrochemical industries sued to stop the EPA
The courts upheld the EPA’s regulations
U.S. CO2 emissions decreased by 12% from 2007 to (partly because of the economic recession, partly from cleaner burning fuels and more efficient cars)

41. Industrializing nations are suffering increasing pollution
Outdoor pollution is getting worse in developing nations
Growing numbers of factories and power plants pollute
Governments emphasize economic growth, not pollution control
People burn traditional fuels (wood and charcoal)
Residents of Mexico City and other Mexican cities suffer a variety of health impacts from the heavily polluted air
China has the world’s worst air pollution
Coal burning, more cars, power plants, factories
Causes over 300,000 premature deaths/year

42. Industrializing nations are suffering increasing pollution
In Beijing in January–February 2013, smog became so thick that residents wore face masks to breath and airplane flights were canceled
The U.S. embassy’s air pollution monitor recorded a measurement of 755 on a scale from 0–500
The health impacts of air pollution across China are huge
A 2013 report blamed 1.2 million premature deaths per year on air pollution
Winds carry the pollution to neighboring countries and even across the Pacific Ocean to the U.S. west coast

44. Industrializing nations are suffering increasing pollution
The government is trying to decrease pollution
Shutting down heavily polluting factories and mines
Phasing out some subsidies for polluting industries
Installing pollution controls in factories
Encouraging renewable and nuclear energy
Mandating cleaner burning fuels
Asian (Atmospheric) Brown Cloud = a 2-mile-thick layer of pollution over southern Asia
Reduces sunlight reaching the ground by 10–20%
Decreased crop productivity, increased flooding, etc.

45. Smog poses health risks
Smog = an unhealthy mixture of air pollutants over urban areas
Industrial smog = smog created when industries burn coal or oil
Carbon monoxide and soot are produced
Sulfur reacts with water to form sulfuric acid, and nitrogen compounds also contribute

46. Smog poses health risks
Smog combined with a thermal inversion killed 21 and sickened 6000 people in Donora, PA in 1948
Industrial smog is now rare in industrialized nations
Coal-burning industrializing countries face smog risks because of coal burning and lax pollution control

48. Smog poses health risks
In urban areas, pollution results mainly from automobile exhaust
Photochemical smog = smog produced when sunlight drives a series of reactions involving primary pollutants
Produces over 100 different chemicals
Tropospheric ozone is often the most abundant
NO2 causes photochemical smog to form a brown haze
Exhaust from morning traffic releases nitric oxide (NO) and VOCs into the air
Photochemical smog typically peaks in the afternoon
Can cause eye, nose, and throat irritation

50. We can take steps to reduce smog
California has lead the way in adopting pollution control technology and emissions standards for vehicles
New cars generate just 1% of the smog-forming emissions of a 1960s car
California and 33 other states require vehicle exhaust inspections, cutting emissions by 30% in many states

51. We can take steps to reduce smog
Other countries are trying to reduce their emissions, requiring cleaner industrial facilities or closing those that can’t improve or providing financial incentives to replace aging vehicles
Increased public transit and bike use
Mexico City has reduced its smog by over 50% since 1990

53. A Case Study…

54. Central Case Study: Cleaning the Air in L.A. and Mexico City
Vehicles caused smog in Los Angeles from 1970s to 1990s
Policies and technologies improved its air quality
But its “sister cities” are not as clean
Mexico City suffered the most polluted air in the world
Vehicles generated most of the pollution
The city is also surrounded by mountains and is at a high elevation, increasing solar radiation

55. Central Case Study: Cleaning the Air in L.A. and Mexico City
Government policies sought to stop the pollution
Shifted industries to cleaner burning fuels
Vehicle emissions were regulated and monitored
New subway lines were added and more efficient busses replaced older ones
Bike rental and car sharing programs were started
Most pollutants have been cut by over 75%
Air meets health standards 1 out of every 2 days (compared to 8 days in all of 1991)
But there is still work to be done; air pollution contributes to an estimated 4000 deaths per year